#include <iostream>

using namespace std;

double cube(double a);
double refcube(double &ra);

int main()
{
    double x = 3.0;
    cout << cube(x) << " = cube of " << x << endl;
    cout << refcube(x) << " = cube of " << x << endl;

    return 0;
}
double cube(double a)
{
    a *= a * a;
    return a;
}

double refcube(double &ra)
{
    ra *= ra * ra;
    return ra;
}
